The development of methods for measuring the efficiency of gas-plasma decontamination has lagged far behind application. An approach to measuring the efficiency of protein removal from solid surfaces using fluorescein-labelled bovine serum albumin and epifluorescence scanning (EFSCAN) is described. A method for fluorescently labelling proteins, which are adsorbed and denatured on metal surfaces, has been developed. Both approaches have been used to evaluate the efficiency of radio frequency (RF) gas-plasma decontamination protocols. Examples with 'real' surgical instruments demonstrate that an argon-oxygen RF gas-plasma treatment can routinely reduce the protein load by about three orders of magnitude beyond that achieved by current decontamination methods.